1. Field of the Invention
The present invention relates to solid propellants for rocket motors and to rocket motors containing the propellants. The invention is equally applicable to cartridge loaded propellants which are fitted in rather than bonded to a rocket motor casing, and to case-bonded propellants, which are bonded directly to the motor casing or more usually to an insulation lining inside the motor casing.
2. Description of Prior Art
Hitherto, solid propellant rocket motors have frequently exhibited the phenomenon of unstable burning which can produce pressure fluctuations in the motor combustion chamber of an amplitude sufficient to rupture the motor casing. The pressure fluctuations have also produced undesirable variations in the thrust resulting from disturbances in the burning mode of the propellant. Thus the motor performance is then extremely unpredictable.
Resonance rods and baffles have been used in rocket motors for the suppression of unstable burning. However, the use of these in rocket motors comprises optimum design of the motor by the addition of inert weight to the motor.
It is also known to include metal particles, usually aluminium particles which have a size of the order of 10 microns, in the propellant grain for the suppression of unstable burning, but this has the disadvantage of producing excessive smoke in the motor exhaust. In addition, the burning rate is affected by the aluminium, and radio frequency signals transmitted to the motor guidance and control systems through the motor exhaust are attenuated and modulated.